Codeforces Beta Round #27 (Codeforces format, Div. 2)
http://codeforces.com/contest/27
A
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define maxn 1000005 7 typedef long long ll; 8 typedef unsigned long long ull; 9 const ull MOD=257; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int a[3005]; 15 16 int main(){ 17 #ifndef ONLINE_JUDGE 18 // freopen("1.txt","r",stdin); 19 #endif 20 std::ios::sync_with_stdio(false); 21 int n; 22 cin>>n; 23 for(int i=1;i<=n;i++){ 24 cin>>a[i]; 25 } 26 sort(a+1,a+n+1); 27 int i; 28 for(i=1;i<=n;i++){ 29 if(a[i]!=i){ 30 cout<<i<<endl; 31 break; 32 } 33 } 34 if(i==n+1) cout<<n+1<<endl; 35 }
B
找出度数大的那个点
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define maxn 1000005 7 typedef long long ll; 8 typedef unsigned long long ull; 9 const ull MOD=257; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int book[55][55]; 15 int n; 16 int d[55]; 17 18 void Check(int &x,int &y){ 19 for(int i=1;i<=n;i++){ 20 for(int j=1;j<=n;j++){ 21 if(i==j) continue; 22 if(!book[i][j]){ 23 x=i,y=j; 24 return; 25 } 26 } 27 } 28 } 29 30 int main(){ 31 #ifndef ONLINE_JUDGE 32 freopen("1.txt","r",stdin); 33 #endif 34 std::ios::sync_with_stdio(false); 35 cin>>n; 36 int nn=n*(n-1)/2-1; 37 int u,v; 38 for(int i=1;i<=nn;i++){ 39 cin>>u>>v; 40 book[u][v]=book[v][u]=1; 41 d[u]++; 42 } 43 int x,y; 44 Check(x,y); 45 if(d[x]>d[y]){ 46 cout<<x<<" "<<y<<endl; 47 } 48 else{ 49 cout<<y<<" "<<x<<endl; 50 } 51 }
C
模拟
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define maxn 1000005 7 typedef long long ll; 8 typedef unsigned long long ull; 9 const ull MOD=257; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int a[100005]; 15 int n; 16 17 int Check(){ 18 int flag=0; 19 for(int i=1;i<n;i++){///<<<<<< 20 if(a[i]>a[i+1]){ 21 flag=1; 22 } 23 } 24 if(flag==0){ 25 return 1; 26 } 27 flag=0; 28 for(int i=1;i<n;i++){///>>>>>> 29 if(a[i]<a[i+1]){ 30 flag=2; 31 } 32 } 33 if(flag==0) return 2; 34 return -1; 35 } 36 37 struct sair{ 38 int v,pos; 39 }b[100005]; 40 int main(){ 41 #ifndef ONLINE_JUDGE 42 // freopen("1.txt","r",stdin); 43 #endif 44 std::ios::sync_with_stdio(false); 45 cin>>n; 46 int co=1; 47 for(int i=1;i<=n;i++){ 48 cin>>a[i]; 49 if(a[i]!=a[i-1]){ 50 b[co].v=a[i]; 51 b[co].pos=i; 52 co++; 53 } 54 } 55 co--; 56 int flag=Check(); 57 if(flag==1||flag==2){ 58 cout<<0<<endl; 59 } 60 else{ 61 cout<<3<<endl; 62 63 for(int i=2;i<co;i++){ 64 if(b[i-1].v>b[i].v&&b[i].v<b[i+1].v){ 65 cout<<b[i-1].pos<<" "<<b[i].pos<<" "<<b[i+1].pos<<endl; 66 break; 67 } 68 if(b[i-1].v<b[i].v&&b[i].v>b[i+1].v){ 69 cout<<b[i-1].pos<<" "<<b[i].pos<<" "<<b[i+1].pos<<endl; 70 break; 71 } 72 } 73 } 74 }
D
用类似二分染色的思想，把交叉的道路染成不同的颜色，如果判断的时候出现交叉的道路有相同的颜色，就输出Impossible
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define pb push_back 7 #define maxn 1000005 8 typedef long long ll; 9 typedef unsigned long long ull; 10 const ull MOD=257; 11 /*#ifndef ONLINE_JUDGE 12 freopen("1.txt","r",stdin); 13 #endif */ 14 15 vector<int>ve[105]; 16 int n,m; 17 int s[105],t[105]; 18 int vis[105]; 19 int col[105]; 20 21 void dfs(int pos,int c){ 22 if(vis[pos]) return; 23 vis[pos]=1; 24 col[pos]=c; 25 for(int i=0;i<ve[pos].size();i++){ 26 dfs(ve[pos][i],c^1); 27 if(col[pos]==col[ve[pos][i]]){ 28 cout<<"Impossible"<<endl; 29 exit(0); 30 } 31 } 32 } 33 34 int main(){ 35 #ifndef ONLINE_JUDGE 36 // freopen("1.txt","r",stdin); 37 #endif 38 std::ios::sync_with_stdio(false); 39 cin>>n>>m; 40 for(int i=1;i<=m;i++){ 41 cin>>s[i]>>t[i]; 42 if(s[i]>t[i]) swap(s[i],t[i]); 43 } 44 for(int i=1;i<=m;i++){ 45 for(int j=1;j<=m;j++){ 46 if(s[i]<s[j]&&t[i]<t[j]&&s[j]<t[i]){ 47 ve[i].pb(j); 48 ve[j].pb(i); 49 } 50 } 51 } 52 for(int i=1;i<=m;i++){ 53 dfs(i,0); 54 } 55 for(int i=1;i<=m;i++){ 56 if(col[i]) cout<<'i'; 57 else cout<<'o'; 58 } 59 }
E
知识点：反素数
参考博客：https://www.cnblogs.com/handsomecui/p/5017484.html
1 #include<bits/stdc++.h> 2 using namespace std; 3 #define lson l,mid,rt<<1 4 #define rson mid+1,r,rt<<1|1 5 #define sqr(x) ((x)*(x)) 6 #define maxn 1000005 7 typedef long long ll; 8 typedef unsigned long long ull; 9 const ull MOD=257; 10 /*#ifndef ONLINE_JUDGE 11 freopen("1.txt","r",stdin); 12 #endif */ 13 14 int prim[16]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53}; 15 int n; 16 ull ans=-1; 17 18 void dfs(int pos,ull v,int num){ 19 if(num==n&&ans>v) ans=v; 20 for(int i=1;i<=63;i++){ 21 if(num*(i+1)>n||v*prim[pos]>ans) break; 22 v*=prim[pos]; 23 dfs(pos+1,v,num*(i+1)); 24 } 25 } 26 27 int main(){ 28 #ifndef ONLINE_JUDGE 29 // freopen("1.txt","r",stdin); 30 #endif 31 std::ios::sync_with_stdio(false); 32 cin>>n; 33 dfs(0,1,1); 34 cout<<ans<<endl; 35 }